1. Field of Invention
The present invention relates to an alpine ski boot having a cuff pivotally mounted on a shell base for rotation about a lower transverse axis substantially coincident with the ankle of the wearer of the boot.
2. Description of Background and Relevant Information
Alpine ski boots often incorporate shock absorption apparatus for controlling flexional forces transmitted by the skier during anterior-posterior flexion of the cuff relative to the shell base of a boot. Conventional shock absorption apparatus for controlling such flexional forces can be classified into two separate groups. In one group are found shock absorbers which are responsive to forward movement of the cuff for returning the same to its initial position; and in this group are found apparatus described in French Patent No. 2,096,248 and European Patent No. 172,156. The shock absorption apparatus of this first group generally comprise an elastic element operative to oppose, with a predetermined force, flexional movement of the cuff on the shell base during forward leg movement, and which instantaneously restores the upper to its initial position as soon as the forward movement terminates. Such apparatus thus comprise an elastic suspension adapted to cushion only forward leg movements; and as a result, the "return" of the upper imposes a relatively severe stress on the leg of the skier. As a consequence, such apparatus is often poorly adapted to the needs of a skier; and moreover, such apparatus cannot be controlled by the skier and is not desired for this reason. In such apparatus, where the "return" occurs in response to relative movement of the cuff of the boot with respect to the shell base, the elastic element involved in the return is positioned between these two portions of the boot.
In a second group of shock absorption apparatus are found what is termed "double effect" shock absorption apparatus which produce a rearward return force which varies in accordance with the extent of forward flexional movement. Such apparatus is described in French Patent No. 2,073,201 and European Patent Application No. 53,339. "Double effect" shock absorption apparatus overcome the disadvantage of shock absorption apparatus of the first group, and particularly the severe "return" of the cuff to its initial position. In addition, "double effect" shock absorption apparatus avoid the floating sensation associated with apparatus of the first group which occurs on the termination of flexional bias on the cuff which occurs with apparatus in the first group. However, the shock absorption apparatus disclosed in the last mentioned documents utilize hydraulic fluids, and are thus both complicated and expensive to manufacture and maintain.
Another "double effect" shock absorption apparatus is described in European Patent No. 135,184. This apparatus comprises two engaged elements, one attached to the cuff and the other attached to the shell base so that relative movement occurs between the elements during displacement of the upper relative to the shell base. The contact pressure between the two elements is adjustable for controlling the coefficient of friction between the elements, and thus the resistance to relative movement. Such shock absorption apparatus has the advantage of structural simplicity which produces manufacturing costs and weight. The disadvantage, however, is that the coefficient of friction between the two elements is the same in both directions of movement of the cuff on the shell base. Thus, the resistance which opposes forward flexional leg movement is the same as that which opposes the return movement of the cuff to its initial position. This equal resistance to movement in the two directions is disadvantageous in skiing.
It is therefore an object of the present invention to provide a new and improved alpine ski boot in which the disadvantages of the prior art described above are substantially reduced or overcome.